1. Field of the Invention
This invention pertains to the use of wire screens ultrasonically welded or otherwise attached to individual module block LED arrays for the purpose of contrast enhancement.
2. Description of the Prior Art
In the prior art, it is known to use a wire screen placed directly in front of an LED display in order to enhance the contrast of the displayed image and to reduce glare. The wire screen achieves these advantages by absorbing a large portion of the ambient light without changing the color of the emitted light. Similarly, the screen filters out off-peak frequencies so that the color of the emitted light is purer than otherwise. Additionally, the wire screen can act as a radiator to reduce the temperature of the operating LED and therefore increase the life of the LED. The wire screen can also reduce EMI if an electrical path to ground is provided.
In the prior art, the installation of the screen is done after the plurality of module block LED arrays have been arranged into a large display and a single large piece of wire screen is fastened to the entire display. However, this can be deficient in larger displays due to the size of the wire screen involved. The large pieces of wire screen can be difficult to obtain, to handle and to install. Moreover, holding the entire wire screen taut can be difficult in larger displays. Any sagging of the wire screen can lead to distortion in the image which makes the dots of module block LED arrays appear non-uniform.
The use of a single screen for a large display of module block LED arrays further increases the difficulty of maintenance of the display in that the screen must be removed to access the module block LED arrays.
Other attempts to enhance contrast have included the use of etched glass which is deficient in that the heat of the LEDs is not adequately dissipated. The use of dark or colored glass has the further disadvantage of changing the color purity of the emitted light.
Miniature louvers have also been used in the prior art but are expensive and difficult to use for large-scale displays.
It is therefore an object of this invention to provide a device for enhancing contrast in a display of module block LED arrays, without limitation on the size of the display.
It is therefore a further object of this invention to provide a device for reducing glare in a display of module block LED arrays.
It is therefore a further object of this invention to provide a contrast enhancement device for a display of module block LED arrays which does not impair the color purity of the emitted light.
It is therefore a further object of this invention to provide a contrast enhancement device for a display of module block LED arrays which is not prone to distorting the displayed image.
It is therefore a still further object of this invention to provide a device which reduces the operating temperature of a display of module block LED arrays.
It is therefore a still further object of this invention to provide a contrast enhancement device for a display of module block LED arrays which does not substantially increase the difficulty of maintenance of the display.
It is therefore a still further object of this invention to provide a device which has the potential for reducing EMI from a display of module block LED arrays.
It is therefore a final object of this invention to provide a contrast enhancement device for a display of module block LED arrays which is low in cost and simple to install.
These and other objects are attained by providing a piece of metallic wire screen which has been dye-cut to the size of the front face of a module block LED array and ultrasonically welded or otherwise attached to the front face of a module block LED array. This ultrasonic welding or other attachment is preferably done as part of the manufacturing process, or at least prior to the assembly of the display from the plurality of module block LED arrays. The attachment of the individual dye-cut pieces of screen to the individual module block LED arrays allows the resulting display to reach unlimited size without causing the disadvantages associated with using a single piece of screen for the entire display xe2x80x94unavailability of large screen sizes, difficulty in installing large screen sizes, difficulty in maintaining the tautness of the screen on the display, difficulty in servicing the display.
The individual dye-cut pieces of screen, however, achieve the advantages of contrast enhancement, glare reduction, color purity, lack of distortion in the display image, heat dissipation and the possibility of EMI reduction.
Moreover, the individual dye-cut pieces of screen are relatively simple to install and do not substantially increase the difficulty of maintenance of the resulting display.
These advantages are achieved at very low cost.